Diode with insulated anode regions

ABSTRACT

A diode is integrated on a semiconductor chip having anode and cathode surfaces opposite to each other. The diode comprises a cathode region extending inwardly from the cathode surface, a drift region extending between the anode surface and the cathode region, and a plurality of anode regions extending from the anode surface in the drift region. The diode further comprises a cathode electrode coupled with the cathode region, and an anode electrode that contacts one or more contacted anode regions of said anode regions and is electrically insulated from one or more floating anode regions of the anode regions. The diode is configured so that charge carriers are injected from the floating anode regions into the drift region in response to applying of a control voltage exceeding a threshold voltage.

BACKGROUND

1. Technical Field

The present disclosure relates to the field of electronics. In greaterdetail, the present disclosure relates to a diode.

2. Description of the Related Art

Diodes are electronic components widely used in various electroniccircuits. For example, in the field of power electronics diodes (alsoreferred to as high voltage diodes) are used for implementing rectifiercircuits and protection circuits. For example, a particular applicationof diodes in the power electronics field is in switching mode powersupplies (SMPS), such as flyback, buck, boost converters, etc., whichare used to supply energy to circuits of various types (e.g., from dataprocessing circuits to LED lighting systems); switching power supplieshave a high efficiency and compactness compared with, for example, theclassic power supplies simply comprising a ferromagnetic transformer.

Switching power supplies provide current and voltage at well-defined andstable values from a supply voltage (e.g., a main voltage) thanks to ahigh frequency switching (in the order of hundreds of KHz) between twoor more operating conditions (e.g., an energy storing condition and anenergy supplying condition). In particular, the energy conversionefficiency of the switching power supply increases with the switchingfrequency thereof. For this reason, in the art there is a continuoustendency to increase the switching frequency of the switching powersupplies.

Therefore, the diodes used in switching power supplies (or moregenerally in any power electronics applications such as in insulatedgate bipolar transistors (IGBT), power MOSFETs and thyristors) should beable to operate properly and with high performance at high frequencies.

Among high voltage diodes, the most widespread type is that known asPiN; a PiN diode comprises an anode region (P) of semiconductor materialwith p-type doping and a cathode region (N) of semiconductor materialwith n-type doping, between which a drift region (i) of semiconductormaterial with a weak n-type doping (lower than the n-type doping of thecathode) is interposed. Theoretically, the intermediate region of PiNdiodes is an undoped intrinsic semiconductor region, hence thedesignation PiN, but PiN diodes are typically made using weak n-typedoping in the intermediate/drift region. The drift region allows acorrect operation even with high potential differences applied to theends of the PiN diode (e.g., in the order of hundreds of Volts). Inorder to operate with high current intensity (e.g., in the order of tensof Amperes) the PiN diode is generally provided with a cellular-typestructure with a plurality of anode regions electrically coupled butspaced apart one from the other.

The PiN diodes may have sub-optimal reverse recovery performance. Infact, when a control voltage of a PiN diode is switched from a forwardbiasing value to a shutdown or reverse biasing value, the chargecarriers (electrons and holes) inside the drift region should be removedbefore the diode prevents a flow of electric current. This has anegative effect on a maximum switching frequency achievable by the PiNdiode.

In order to increase the removal speed of the charge carriers of the PiNdiodes (and hence the reverse recovery performance), in the art variouschanges to their structure have been proposed. In general, the knownchanges are based on introductions of recombination centers for thecharge carriers in the drift region (called lifetime killing technique)and/or on variation of the structure of the anode and/or the cathode,e.g., buffer, Hybrid or ECPT (Collector Emitter Punch-Through) cathodestructures and/or SSD (Static Shielding diode), MPS (Merged PiN Schottkydiode), Speed (Self-Adjusting P-Emitter Efficiency diode), SFD (Soft andFast Diode), ESD (Short Emitter Diode) and CIC (Charge InjectionControl) anode structures.

However, the introduction of recombination centers generally increasesleakage currents due to non-ideality of the PiN diodes. The solutionsthat modify the cathode structure generally increase a peak intensity ofa reverse current generated during the reverse recovery phase. Finally,the solutions that modify the anode structure generally increase athreshold voltage required to activate the PiN diodes.

BRIEF SUMMARY

A simplified summary of the present disclosure is herein presented inorder to provide a basic understanding thereof; however, the solepurpose of this summary is to introduce some concepts of the disclosurein a simplified form as a prelude to its following more detaileddescription, and it is not be understood as an indication of its keyelements nor as a delimitation of its scope.

In general terms, the present disclosure is based on the idea ofinsulating part of the anode regions.

In particular, an aspect of the present disclosure provides a diode, inwhich one or more anode regions are electrically coupled with an anodeelectrode, and one or more anode regions are electrically insulatedtherefrom.

Another aspect provides an electronic device comprising at least onediode mentioned above and at least one power transistor integrated on asame chip.

A different aspect provides an electronic apparatus comprising at leastone electronic device mentioned above.

A further aspect provides a method of integrating such diode on a chipof semiconductor material.

In particular, one or more aspects of the present disclosure are set outin the independent claims and advantageous features thereof are set outin the dependent claims, with the wording of all the claims that isherein incorporated verbatim by reference (with any advantageousfeatures provided with reference to a specific aspect that apply mutatismutandis at any other aspect).

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The solution of the present disclosure, as well as additional featuresand its advantages, will be better understood with reference to thefollowing detailed description, given purely by way of indication andwithout limitation, to be read in conjunction with the attached figures(wherein corresponding elements are denoted with equal or similarreferences and their explanation is not repeated for the sake ofbrevity). In this respect, it is expressly intended that the figures arenot necessarily to scale (with some details that may be exaggeratedand/or simplified) and that, unless otherwise indicated, they are simplyused to conceptually illustrate the described structures and procedures.In particular:

FIG. 1 shows a schematic cross-section side view of a PiN diodeaccording to an embodiment of the present disclosure;

FIG. 2 shows a schematic cross-section side view of a PiN diodeaccording to another embodiment of the present disclosure;

FIG. 3 shows a schematic top plan view of a PiN diode according to anembodiment of the present disclosure;

FIG. 4 shows a schematic top plan view of a PiN diode according to afurther embodiment of the present disclosure;

FIG. 5 shows a schematic top plan view of a PiN diode according toanother further embodiment of the present disclosure;

FIG. 6 shows a qualitative graph of a trend of the current/voltagerelationship in the PiN diode according to an embodiment of the presentdisclosure;

FIG. 7 shows a qualitative graph of a concentration of minority carriersin the PiN diode according to an embodiment of the present disclosure,and

FIG. 8 shows a qualitative graph of a trend of an electric current in aswitching phase in the structure of the PiN diode according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

With reference to FIG. 1, it illustrates a schematic cross-section sideview of a PiN diode 100 according to an embodiment of the presentdisclosure.

The PiN diode 100 (e.g., for power applications) is integrated on a chipof semiconductor material 105, such as silicon Si; the chip 105 has two(main) surfaces opposite to each other, indicated as cathode (lower)surface 105 c and as anode (upper) surface 105 a. The diode has acathode electrode 110 and an anode electrode 115 of electricallyconductive material (e.g., one or more layers of metallic and/or heavilydoped semiconductor material).

The PiN diode 100 comprises a cathode region 120 (or more) having ann-type doping (e.g., silicon doped with phosphorus P). The cathoderegion 120 extends from the cathode surface 105 c toward the inside ofthe chip 105. The cathode region 120 is electrically coupled with thecathode electrode 110 on the cathode surface 105 c.

An drift region 130 extends in the chip 105 between the cathode region120 and the anode surface 105 a. The drift region 130 has a dopingsimilar to the doping of the cathode region, i.e., of the same n-type,but with a concentration of dopants (namely, a number of phosphorusatoms compared with the silicon atoms) lower than a dopant concentrationof the cathode region 120. For example, the doping of the drift region130 is equal to 10⁻¹⁰-10⁻³ times, preferably equal to 10⁻⁹-10⁻⁴ times,and still more preferably equal to 10⁻⁸-10⁻⁵ times, such as equal to10⁻⁶ times, the doping of the cathode region 120; for example, thedoping of the drift region 130 is in the order of 10¹³ carriers/cm³ andthe doping of the cathode region 120 is in the order to 10¹⁹carriers/cm³.

A plurality of anode regions 135 extends from the anode surface 105 a inthe chip 105.

The anode regions 135 are formed of semiconductor material having adoping of the opposite type with respect to the doping of the cathoderegion 120, i.e., p-type (such as silicon doped with boron B, e.g., witha concentration of 10¹⁵-10¹⁷ carriers/cm³).

In the solution according to an embodiment of the present disclosure, asubset of (one or more) anode regions 135 (referred to as contactedanode regions 135 c) is electrically coupled with the anode electrode115 on the anode surface 105 a (as usual); however, another (remaining)subset of (one or more) anode regions 135 (referred to as floating anoderegions 135 f) is electrically insulated from the anode electrode 115.In particular, in the specific embodiment shown in the figure, eachfloating anode region 135 f is interposed between a pair of adjacentcontacted anode regions 135 c.

For example, the anode surface 105 a is covered by an insulating layer140 made of an electrically insulating material (e.g., silicon oxide).The insulating layer 140 is interposed between the anode surface 105 aand the anode electrode 115 in correspondence to the floating anoderegions 135 f, while contact windows (for the anode electrode 115) areopened in the insulating layer 140 in correspondence to the contactedanode regions 135 c. In this way, the floating anode regions 135 f (andthe drift region 130) are insulated from the anode electrode 115.

The PiN diode 100 is configured in such a way that, when a controlelectric voltage, applied between the anode electrode 105 a and thecathode electrode 105 c, has a positive value (forward voltage Vd) thatexceeds a threshold voltage of the diode PiN 100 (e.g., in the order ofsome Volts, for example, 0.8-5.0 V, preferably 0.8-2.5 V, and even morepreferably 0.8-2.0V), the charge carriers (holes) comprised in thefloating anode regions 135 f are injected from the latter into the driftregion 130. Such injection of the holes from the floating anode regions135 f in the drift region 130 occurs in response to the reaching of thefloating anode regions 135 f by an electric field E generated betweenthe contacted anode regions 135 c and the cathode region 120 by theapplication of the forward voltage Vd.

For this purpose each floating anode region 135 f is spaced apart on theanode surface 105 a from each adjacent contacted anode region 135 c atmost by 1-30 μm, preferably 1-20 μm, and even more preferably 0.5-10 μm,such as 5 m.

In this way, in the drift region 130 the holes injected from thefloating anode regions 135 f are added to the holes injected (as it isknown) from the contacted anode regions 135 c, thereby obtaining ahigher hole concentration (compared to a known PiN diode). This, for thesame voltage Vd, increases the intensity of a corresponding current ofthe PiN diode (also a positive one, or forward current Id). All this hasa positive effect on the efficiency of the PiN diode 100 during aforward operation thereof.

In addition, it also improves the reverse recovery performance of thePiN diode 100; this result is obtained without (or with limited)increase of leakage currents, increase of peak intensity of a reversecurrent generated during the reverse recovery phase and increase of thethreshold voltage.

All this has a positive effect on a maximum switching frequencyreachable by the PiN diode 100, so that it is particularly advantageousin switching mode power supplies.

Turning to FIG. 2, it illustrates a schematic cross-section side view ofa PiN diode 200 according to another embodiment of the presentdisclosure.

The PiN diode 200 differs from the PiN diode just described in whatfollows.

In the PiN diode 200, a plurality of floating anode regions 135 f, twoin the example at issue, is formed between each pair of adjacentcontacted anode regions 135 c.

The structure described above allows injecting an even greater number ofholes from the floating anode regions 135 f into the drift region 130for the same value of the forward voltage Vd (compared to the previouscase).

It should be noted however that as the number of floating anode regions135 f between each pair of contacted anode regions 135 c increases avalue of a breakdown voltage Vb of the diode decreases. For example, abreakdown voltage Vb exceeding 1.2-2.5 kV is obtained with a number offloating anode regions 135 f between each pair of contacted anoderegions 135 c lower than 4-5.

Considering now FIG. 3, it illustrates a schematic top plan view of thePiN diode 100 according to an embodiment of the present disclosure.

In detail, the anode regions 135 are shaped as substantially parallelstripes on the surface 115. Preferably, each anode region 135 has alongitudinal extent y substantially greater than a transversal extent x.For example, a ratio between the longitudinal extent y and thetransversal extent x is greater than 10-200, such as equal to 50.

Furthermore, the anode electrode 115 has a structure of perimetral-type,i.e., it is shaped substantially as a frame, disposed in such a way tosurround (in plan) the anode regions 135 c, 135 f and to surmountopposite ends of each of them (with the ends of each floating anoderegion 135 f that are insulated from the anode electrode 115 thatsurmounts them through the insulating layer 140 and with the ends ofeach contacted anode region 135 c that are electrically coupled with theanode electrode 115 by means of corresponding windows opened in theinsulating layer 140).

This has a positive effect on the operation of the PiN diode 100.Indeed, the contact between the anode electrode 115 at the opposite endsof each contacted anode region 135 c ensures a more homogeneousdistribution of the forward current Id along the length of the contactedanode regions 135 c and the floating anode regions 135 f.

In addition, thanks to the structure described above, the electric fieldE is more uniform as well.

Similar considerations apply when this configuration is applied to thestructure of FIG. 2 (not shown in the figures), so that two or morestrips of floating anode regions are interposed between each pair ofstrips of adjacent contacted anode regions.

Considering FIG. 4, it illustrates a schematic top plan view of the PiNdiode 100 according to a further embodiment of the present disclosure.

In this case, the anode regions 135 are formed substantially with an“island” structure on the anode surface 105 a. In other words, eachanode region 135 c has a longitudinal extent y′ substantially equal to alateral extent x′. For example, a ratio between the longitudinal extenty′ and the lateral extent x′ is lower than 2-5, such as, for example,equal to 1.

Preferably, the anode regions 135 c, 135 f are arranged on the anodesurface 105 a with a matrix arrangement (i.e., in rows and columns).

In the embodiment shown in the figure, the floating anode regions 135 fand the contacted anode regions 135 c are arranged along correspondingalignments 450 f and 450 c, respectively (e.g., columns of the matrix).Each alignment 450 f of floating anode regions 135 f is comprisedbetween a pair of adjacent alignments 450 c of the contacted anoderegions 135 c.

In this way, the same benefits as described above may be obtained evenif the anode regions 135 are formed with an island structure.

Similar considerations apply when such configuration is applied to thestructure of FIG. 2 (not shown in the figures), so that two or morearrays of floating anode regions are comprised between each pair ofarrays of adjacent contacted anode regions as above.

Turning to FIG. 5, it illustrates a schematic top plan view of the PiNdiode 100 according to another further embodiment of the presentdisclosure.

As above, the anode regions 135 are arranged on the anode surface 105 awith a matrix arrangement. However, in this case each floating anoderegion 135 f is surrounded on the anode surface 105 a by a plurality ofcontacted anode regions 135 c. For example, each floating anode region135 f is comprised between respective pairs of adjacent contacted anoderegions 135 c arranged along the longitudinal direction, along thetransversal direction and along the diagonal directions (transverse toeach other) on the anode surface 105 a.

In this way, it is possible to obtain a greater uniformity of theelectric field E which extends in the floating anode regions 135 fsurrounded by the contacted anode regions 135 c, thereby obtaining agreater hole injection efficiency.

Similar considerations apply when this configuration is applied to thestructure of FIG. 2 (not shown in the figures), so that the floatinganode regions are organized into sets each of two or more floating anoderegions; each set of floating anode regions is surrounded by a pluralityof contacted anode regions.

With reference now to FIG. 6, it illustrates a qualitative graph thatplots the forward current Id of the diode (on the ordinate axis) as afunction of the forward voltage Vd applied between its anode and cathodeelectrodes (on the abscissa axis), or Id/Vd characteristic; inparticular, a curve 600 i represents the trend of the (forward)current/voltage relationship in the PiN diode according to an embodimentof the present disclosure, while a curve 600 n represents the trend ofthe current/voltage relationship in a PiN diode known in the art (withthe same anode regions being all contacted). As mentioned above, the PiNdiode according to an embodiment of the present disclosure allowsobtaining a forward current Id (represented by the curve 600 i) ofhigher intensity for the same voltage Vd compared to the known PiN diode(represented by the curve 600 n).

Similarly, FIG. 7 illustrates a qualitative graph that plots aconcentration of minority carriers Nh in the drift region (on theordinate axis) as a function of the depth z therein (on the abscissaaxis); in particular, a curve 700 i represents the trend of theconcentration in the PiN diode according to an embodiment of the presentdisclosure, whereas a curve 700 n represents the trend of theconcentration in a PiN diode known in the art (with the same anoderegions being all contacted) during the forward operation. As it may beappreciated, the concentration in the PiN diode according to anembodiment of the present disclosure (represented by the curve 700 i) issubstantially greater than the concentration in the PiN diode known inthe art (represented by the curve 700 n), in particular starting fromthe anode surface 105 a toward the cathode surface 105 c for apredominant portion of the drift region 130. Such increasedconcentration allows obtaining the benefits relating to the Id/Vdcharacteristic mentioned above.

With reference to FIG. 8, it illustrates a qualitative graph of a trendof the electric current in a switching phase in the PiN diode accordingto an embodiment of the present disclosure.

In particular, the figure shows a qualitative graph that plots thecurrent I of the diode (on the ordinate axis) as a function of time t(on the abscissa axis), starting from an instant in which the controlvoltage of the diode (i.e., the voltage applied between its electrodes)is switched from a value higher than the threshold voltage (forwardbiased diode) to a value lower than it (reverse biased diode).

As it is known, at the beginning of the switching the current I (beingpositive, i.e., the forward current Id) starts to decrease, and then itreverses (indicated as reverse current I_(i)) down to reach an intensitypeak I_(rr|pk) (due to the residual charge carriers, both electrons andholes, comprised in the drift region at the beginning of the switchingphase). The current I then decreases in absolute value (referred to asrecombination current Irr at this stage) up to zero at the end of theswitching (as a result of the recombination of the residual chargecarriers).

In an embodiment according to the present disclosure, the improvement ofthe Id/Vd characteristic described above is exploited to improve theswitching performance of the PiN diode.

For example, the improvement of the Id/Vd characteristic may beexploited to cancel, or at least mitigate, the disadvantages connectedto an application of techniques for the reduction of the life time(lifetime killing) of the charge carriers within the drift region of thePiN diode commonly used to reduce the peak intensity I_(rr|pk)

For this purpose, a plurality of charge recombination centers (notshown) is provided in the drift region of the PiN diode (e.g., aconcentration of the charge recombination centers is preferably greaterthan or equal to 10¹²-10¹⁶ centers/cm³, preferably 5×10¹²-5×10¹⁴centres/cm³, such as 10¹³ centres/cm³). The charge recombination centersmay be formed by a doping with impurities (e.g., gold Au or platinum Ptatoms) in the drift region, or by the generation of defects in thecrystalline structure of the drift region (e.g., through irradiationwith an electron beam or electromagnetic radiations, such as y-rays).

The charge recombination centers have the effect of increasing arecombination rate between the charge carriers of opposite polarity(i.e., electrons and holes) within the drift region. Consequently, a netnumber of charge carriers that need to be recombined by therecombination current I_(rr) during the switching phase is reduced, as afunction of the concentration of the charge recombination centers (e.g.,reduced by a percentage greater than or equal to 2-20%, preferably4-15%, and even more preferably 7-13%, such as 10%).

This allows attenuating the peak intensity I_(rr|pk). This also involvesa general reduction of the negative slope of the variation of thereverse current Ii over time (i.e., −dI_(i)/dt) between an instant t₀ inwhich the current I_(i) is canceled and an instant t_(pk) in which thereverse current I_(rr) reaches the peak intensity I_(rr|pk) and also apositive slope of the variation of the recombination current I_(rr)(i.e., dI_(rr)/dt) between the instant t_(pk) and a switching finalinstant t_(f).

However, the addition of the charge recombination centers increases theintensity of leakage currents in the PiN diode due to a recombination ofthe charge carriers that contribute to the forward current Id during theforward operation of the PiN diode.

In the PiN diode according to embodiments of the present disclosure, itis possible to cancel, or at least substantially mitigate, the negativeeffect due to the increase of intensity of the leakage currents.

In fact, the increase of the forward current Id made possible thanks tothe presence of the floating anode regions allows compensating, at leastpartially (or even exceeding) the leakage current caused by the additionof the charge recombination centers. In this way, it is possible to addthe charge recombination centers (with the advantages described above)and still obtain the same forward current Id (for the same voltage Vd)of the PiN diodes known in the art. In this way it is possible to obtaina positive effect on the switching frequency capability of the PiNdiode, thereby improving its efficiency.

In addition or alternatively, it is also possible (in order to furtherincrease the removal speed of the charge carriers) to provide thecathode region with a cathode buffer structure, a cathode hybridstructure and/or an Emitter-Collector Punch-Through (ECPT) cathodestructure and/or part of the (both contact and floating) anode regionswith a Static Shielding Diode (SSD) anode structure, a Merged PiNSchottky diode (MPS) anode structure, a Self-adjusting P-emitterEfficiency Diode (SPEED) anode structure, a Soft and Fast Diode (SFD)anode structure, an Emitter Short Diode (ESD) anode structure and/or aCharge Injection Control (CIC) anode structure.

The PiN diode according to embodiments of the present disclosure isadapted to be integrated together with other electronic components (notshown) on a same chip of semiconductor material in order to provide acomplex integrated electronic device. For example, the PiN diode may beintegrated in parallel to a power transistor (such as a MOSFETtransistor) in order to ensure a correct operation of the latter duringthe rapid changes in voltage at its terminals (for example, suitable forthe use in switching power supplies).

Additionally, one or more PiN diodes according to embodiments of thepresent disclosure and/or the power transistor comprising a PiN diodealso lend themselves to be implemented in power equipments such as diodebridges for rectifying oscillating voltages and/or Switching Mode PowerSupplies (SMPS) such as buck, boost or flyback converters.

Naturally, in order to satisfy local and specific requirements, a personskilled in the art may apply to the solution described above manylogical and/or physical modifications and alterations. Morespecifically, although this solution has been described with a certaindegree of particularity with reference to one or more embodimentsthereof, it should be understood that various omissions, substitutionsand changes in the form and details as well as other embodiments arepossible. Particularly, different embodiments of the invention may evenbe practiced without the specific details (such as the numericalexamples) set forth in the preceding description to provide a morethorough understanding thereof; conversely, well-known features may havebeen omitted or simplified in order not to obscure the description withunnecessary particulars. Moreover, it is expressly intended thatspecific elements and/or method steps described in connection with anyembodiment of the disclosed solution may be incorporated in any otherembodiment as a matter of general design choice. In any case, the termscomprising, including, having and containing (and any of their forms)should be understood with an open and non-exhaustive meaning (i.e., notlimited to the recited elements), the terms based on, dependent on,according to, function of (and any of their forms) should be understoodas a non-exclusive relationship (i.e., with possible further variablesinvolved) and the term a should be understood as one or more elements(unless expressly stated otherwise).

For example, a diode is proposed. The diode is integrated on a chip ofsemiconductor material having an anode surface and a cathode surfaceopposite to each other. The diode comprises at least one cathode regionhaving a doping of a first type, with the cathode region that extendsfrom the cathode surface in the chip. Furthermore, the diode comprises adrift region having a doping of the first type with a dopantconcentration lower than a dopant concentration of the cathode region;such drift region extends between the anode surface and the cathoderegion. In addition, the diode comprises a plurality of anode regionshaving a doping of a second type, with each anode region that extendsfrom the anode surface in the drift region. The diode further comprisesa cathode electrode of electrically conductive material electricallycoupled with said at least one cathode region on the cathode surface,and an anode electrode of electrically conducting material. One or morecontacted anode regions of said anode regions are electrically coupledwith the anode electrode on the anode surface, and one or more floatinganode regions of said anode regions are electrically insulated from theanode electrode. The diode is configured so that charge carriers areinjected from said at least one floating anode region into the driftregion in response to the applying of a control voltage between theanode electrode and the cathode electrode exceeding a threshold voltageof the diode.

However, the diode may be of any type (also not PiN) and may work withany voltage and current values (even at low power); the anode, cathodeand drift regions may be in any number, of any type (standard or not),with any shape (see below), size and doping (in terms both of type ofimpurities and of their relative and absolute amount); similarly, theanode and cathode electrodes may be of any type, material and number(also different from the number of anode and cathode regions,respectively). The cathode region and the contacted anode regions may becoupled with the cathode and anode electrode, respectively, in any way(either directly or indirectly, for example, via conductive paths), andthe floating anode regions may be insulated from the anode electrode inany way (e.g., by means of corresponding insulating elements). Thefloating and contacted anode regions may be in any number (equal to ordifferent from each other) and arranged in any manner (see below).

In an embodiment, the drift region comprises a plurality of chargerecombination centers adapted to recombine free charge carriers.

However, the charge recombination centers may be of any type, in anynumber, size and position. In any case, an implementation without suchrecombination centers (for example, to obtain a greater forward currentfor the same forward voltage) is not excluded.

In an embodiment, the anode regions are shaped in strips parallel toeach other on the anode surface.

Anyway, the strips may have any size and arrangement; For example,nothing prevents from forming a plurality of clusters of parallelstripes, with such clusters formed transversally to each other.

In an embodiment, the floating anode regions are organized into setseach of one or more floating anode regions; each set of floating anoderegions is comprised on the anode surface between each pair of adjacentcontacted anode regions.

However, each set may comprise any number of floating anode regions; inany case, nothing prevents arranging the anode regions in another way(for example, with additional contacted anode regions adjacent to thecontacted anode regions of each pair).

In an embodiment, the anode regions are arranged in a matrix on theanode surface.

However, the matrix may have any number of rows and columns (eitherequal or different one from the other). In any case, the anode regionsmay be arranged in any other way (for example, divided into a pluralityof clusters, in which the anode regions are arranged in different stripsor matrices).

In an embodiment, the floating anode regions are organized into setseach of one or more floating anode regions; each set of floating anoderegions is surrounded along a plurality of directions on the anodesurface by a plurality of contacted anode regions.

However, each set may comprise any number of floating anode regions andmay be surrounded by the contacted anode regions along any number (twoor more) of directions; in any case, nothing prevents the sets offloating anode regions from being surrounded by the plurality ofcontacted anode regions with solution of continuity. Alternatively, thecontacted anode regions and the floating anode regions are formed inalternate positions along both the rows and the columns of the matrixformed by them on the anode surface.

In an embodiment, the contacted anode regions and the floating anoderegions are arranged on the anode surface along corresponding alignmentsparallel to each other. The alignments of the floating anode regions arearranged in sets each of one or more alignments; each set of alignmentsof the floating anode regions on the anode surface is comprised betweeneach pair of adjacent alignments of the contacted anode regions.

However, each set may comprise any number of alignments of the floatinganode regions; in any case, nothing prevents forming a plurality ofclusters each comprising sets of alignments of floating anode regionsand the corresponding alignments of contacted anode regions, eachcluster being disposed transversally to one or more of the remainingclusters on the anode surface.

Moreover, the proposed solution might be part of the design of anintegrated device. The design may also be created in a programminglanguage; in addition, if the designer does not manufacture theintegrated device or its masks, the design may be transmitted throughphysical means to others. Anyway, the resulting integrated device may bedistributed by its manufacturer in the form of a raw wafer, as a nakedchip, or in packages.

A different aspect proposes an electronic device comprising at least onediode, and at least one power transistor integrated on said chip; eachdiode is operatively coupled with a respective power transistor.

However, the electronic device may comprise any number of diodes andpower transistors. In any case, it is possible to provide an electroniccomponent different from a transistor (e.g., a thyristor). In addition,nothing prevents integrating only the diode (or diodes) on the chip.

A different aspect provides an electronic apparatus comprising at leastone electronic device mentioned above.

However, the electronic apparatus may comprise any number of electronicdevices; Moreover, this electronic apparatus may be used in anyapplication (for example, even not of the power type).

Generally, similar considerations apply if the diode, the electronicdevice and the electronic apparatus each has a different structure orcomprises equivalent components (for example, of different materials),or it has other operative characteristics. In any case, every componentthereof may be separated into more elements, or two or more componentsmay be combined together into a single element; moreover, each componentmay be replicated to support the execution of the correspondingoperations in parallel. It should also be noted that (unless specifiedotherwise) any interaction between different components generally doesnot need to be continuous, and it may be either direct or indirectthrough one or more intermediaries.

A further aspect provides a method of integrating a diode on a chip ofsemiconductor material having an anode surface and a cathode surfaceopposite to each other. The method comprising the following steps. Atleast one cathode region having a doping of a first type is formed; thecathode region extends from the cathode surface in the chip therebydefining an drift region having a doping of the first type with a dopantconcentration lower than a dopant concentration of the cathode region(with the drift region extending between the anode surface and thecathode region). A plurality of anode regions having a doping of asecond type is formed; each anode region extends from the anode surfacein the drift region. A cathode electrode of electrically conductivematerial is formed electrically coupled with the at least one cathoderegion on the cathode surface. An anode electrode of electricallyconducting material is formed. The step of forming an anode electrodecomprises the following steps. The anode electrode is formed in such away to electrically couple one or more contacted anode regions of saidanode regions with the anode electrode on the anode surface. One or morefloating anode regions of said anode regions are electrically insulatedfrom the anode electrode. The diode is configured in such a way thatcharge carriers are injected from said at least one floating anoderegion into the drift region in response to the applying of a controlvoltage between the anode electrode and the cathode electrode exceedinga threshold voltage of the diode.

In general, similar considerations may be applied if the same solutionis implemented by an equivalent method (using similar steps with thesame functions of several steps or any portion thereof, by removing somenon-essential steps, or adding additional optional steps); furthermore,the steps may be performed in a different order, in parallel oroverlapped (at least in part).

The various embodiments described above can be combined to providefurther embodiments. These and other changes can be made to theembodiments in light of the above-detailed description. In general, inthe following claims, the terms used should not be construed to limitthe claims to the specific embodiments disclosed in the specificationand the claims, but should be construed to include all possibleembodiments along with the full scope of equivalents to which suchclaims are entitled. Accordingly, the claims are not limited by thedisclosure.

1. A diode integrated on a chip of semiconductor material having ananode surface and a cathode surface opposite to each other, the diodecomprising: a cathode region having a doping of a first type, thecathode region extending from the cathode surface in the chip, an driftregion having a doping of the first type with a dopant concentrationlower than a dopant concentration of the cathode region, the driftregion extending between the anode surface and the cathode region, aplurality of anode regions having a doping of a second type, each anoderegion extending from the anode surface in the drift region, a cathodeelectrode of electrically conductive material on the cathode surface andelectrically coupled with said cathode region, and an anode electrode ofelectrically conducting material, wherein: one or more contacted anoderegions of said anode regions are electrically coupled with the anodeelectrode on the anode surface, and one or more floating anode regionsof said anode regions are electrically insulated from the anodeelectrode, the diode being configured so that charge carriers areinjected from said one or more floating anode regions into the driftregion in response to a control voltage, applied between the anodeelectrode and the cathode electrode, exceeding a threshold voltage ofthe diode, wherein the anode regions are arranged in a matrix on theanode surface.
 2. The diode according to claim 1, wherein the driftregion comprises a plurality of charge recombination centers adapted torecombine free charge carriers.
 3. The diode according to claim 1,comprising an insulating layer covering the one or more floating anoderegions and covering portions of the anode surface between the anoderegions.
 4. The diode according to claim 3, wherein the insulating layerincludes one or more openings directly above the one or more contactedanode regions, respectively, and the anode electrode includes a coveringportion that covers the insulating layer and one or more contactportions extending respectively in the one or more openings andcontacting the one or more contacted anode regions, respectively.
 5. Thediode according to claim 4, wherein the insulating layer contacts all ofthe anode surface between consecutive ones of the one or more contactedanode regions.
 6. The diode according to claim 1, wherein the floatinganode regions are organized into sets each of one or more floating anoderegions, each set of floating anode regions being surrounded along aplurality of directions on the anode surface by a plurality of thecontacted anode regions.
 7. The diode according to claim 1, in which thecontacted anode regions and the floating anode regions are arranged onthe anode surface along corresponding alignments parallel to each other,the alignments of the floating anode regions being arranged in sets eachof one or more alignments, each set of alignments of the floating anoderegions on the anode surface being positioned between each pair ofadjacent alignments of the contacted anode regions.
 8. An electronicdevice comprising: a power transistor integrated on a chip ofsemiconductor material having an anode surface and a cathode surfaceopposite to each other; and a diode operatively coupled with the powertransistor, the diode including: a cathode region having a doping of afirst type, the cathode region extending from the cathode surface in thechip, an drift region having a doping of the first type with a dopantconcentration lower than a dopant concentration of the cathode region,the drift region extending between the anode surface and the cathoderegion, a plurality of anode regions having a doping of a second type,each anode region extending from the anode surface in the drift region,a cathode electrode of electrically conductive material on the cathodesurface and electrically coupled with said cathode region, and an anodeelectrode of electrically conducting material, wherein: one or morecontacted anode regions of said anode regions are electrically coupledwith the anode electrode on the anode surface, and one or more floatinganode regions of said anode regions are electrically insulated from theanode electrode, the diode being configured so that charge carriers areinjected from said one or more floating anode regions into the driftregion in response to a control voltage, applied between the anodeelectrode and the cathode electrode, exceeding a threshold voltage ofthe diode.
 9. The electronic device according to claim 8, wherein thediode includes an insulating layer covering the one or more floatinganode regions and covering portions of the anode surface between theanode regions.
 10. The electronic device according to claim 9, whereinthe insulating layer includes one or more openings directly above theone or more contacted anode regions, respectively, and the anodeelectrode includes a covering portion that covers the insulating layerand one or more contact portions extending respectively in the one ormore openings and contacting the one or more contacted anode regions,respectively.
 11. The electronic device according to claim 10, whereinthe insulating layer contacts all of the anode surface betweenconsecutive ones of the one or more contacted anode regions.
 12. Theelectronic device according to claim 8, wherein the floating anoderegions are organized into sets each of one or more floating anoderegions, each set of floating anode regions being surrounded along aplurality of directions on the anode surface by a plurality of thecontacted anode regions.
 13. The electronic device according to claim 8,in which the contacted anode regions and the floating anode regions arearranged on the anode surface along corresponding alignments parallel toeach other, the alignments of the floating anode regions being arrangedin sets each of one or more alignments, each set of alignments of thefloating anode regions on the anode surface being positioned betweeneach pair of adjacent alignments of the contacted anode regions.
 14. Theelectronic device according to claim 8, wherein the electronic device isa power apparatus configured to supply power to a load.
 15. A method,comprising: integrating a diode in a chip of semiconductor materialhaving an anode surface and a cathode surface opposite to each other,the integrating including: forming a cathode region having a doping of afirst type, the cathode region extending from the cathode surface in thechip thereby defining a drift region having a doping of the first typewith a dopant concentration lower than a dopant concentration of thecathode region, the drift region extending between the anode surface andthe cathode region, forming a plurality of anode regions having a dopingof a second type, each anode region extending from the anode surface inthe drift region, forming a cathode electrode of electrically conductivematerial on the cathode surface and electrically coupled with thecathode region, and forming an anode electrode of electricallyconducting material, wherein forming the anode electrode comprises:forming the anode electrode in such a way to electrically couple one ormore contacted anode regions of said anode regions with the anodeelectrode on the anode surface, and electrically insulating one or morefloating anode regions of said anode regions from the anode electrode,the diode being configured in such a way that charge carriers areinjected from said at least one floating anode region into the driftregion in response to a control voltage, applied between the anodeelectrode and the cathode electrode, exceeding a threshold voltage ofthe diode, wherein the anode regions are arranged in a matrix on theanode surface.
 16. The method according to claim 15, comprising formingan insulating layer covering the one or more floating anode regions andcovering portions of the anode surface between the anode regions. 17.The method according to claim 16, wherein the insulating layer includesone or more openings directly above the one or more contacted anoderegions, respectively, and the anode electrode includes a coveringportion that covers the insulating layer and one or more contactportions extending respectively in the one or more openings andcontacting the one or more contacted anode regions, respectively. 18.The method according to claim 17, wherein the insulating layer contactsall of the anode surface between consecutive ones of the one or morecontacted anode regions e.
 19. The method according to claim 18, whereinthe floating anode regions are organized into sets each of one or morefloating anode regions, each set of floating anode regions beingsurrounded along a plurality of directions on the anode surface by aplurality of the contacted anode regions.
 20. The method according toclaim 18, in which the contacted anode regions and the floating anoderegions are arranged on the anode surface along corresponding alignmentsparallel to each other, the alignments of the floating anode regionsbeing arranged in sets each of one or more alignments, each set ofalignments of the floating anode regions on the anode surface beingpositioned between each pair of adjacent alignments of the contactedanode regions.